Characterization and Optimization of L-Asparaginase Production by Endophytic Fusarium sp3 Isolated From Malcolmia aegyptiaca of Southeast Algeria: Potential for Acrylamide Mitigation in Food Processing.

This study aims to isolate and optimize the production of L-asparaginase from fungal strains derived from Algerian Saharan plants, and evaluate the reduction of acrylamide formation in food products. L-asparaginase has frequently been used to treat childhood acute lymphoblastic leukemia. It catalyzes the hydrolysis of asparagine and glutamine into aspartic acid and ammonia. It is also used in the food industry to minimize acrylamide formation during high-temperature frying of starchy food items. In this study, L-asparaginase was identified in various microbial, animal, and plant species. Using Czapek-Dox medium, different fungal species were first isolated from Saharan plants of southeast Algeria (including Zygophyllum cornutum Coss., Malcolmia aegyptiaca Spreng., Phoenix dactylifera L., and Cyperus rotundus L.) and tested for their ability to produce extracellular L-asparaginase. Among 13 isolates, nine were positive in the preliminary test. The strain Fusarium sp.₃, isolated from M. aegyptiaca leaves, had the highest enzyme index (1.92 ± 0.35) with maximum enzyme production (63.68 units per milliliter). Critical factors such as temperature (30°C-50°C), pH (5.0-8.0), and substrate concentration (1-10 g/L) were optimized under liquid-state fermentation to maximize enzyme production. Utilizing Minitab software, additional statistical methods were employed for the optimization process, including the Plackett-Burman design and response surface methodology. The Plackett-Burman design screened seven variables: temperature, pH, incubation time, substrate concentration, glucose concentration, nitrogen source, and agitation speed. The design identified asparagine concentration, incubation time, and pH as the most significant factors for asparaginase production. Response surface methodology was then used to optimize these factors, producing maximum asparaginase in a 50-mL medium. Under optimized conditions, the application of L-asparaginase to potato slices prior to frying resulted in a 68% reduction in acrylamide content (from 435.6 ± 12.4 μg/kg to 139.3 ± 8.7 μg/kg), demonstrating the enzyme's strong potential for improving food safety.